At this point, I don't know how the car got there, but I think there is more than one possibility. When it got there is perhaps of more importance now. But I don't think fear of leaving evidence is necessarily the reason someone else wouldn't have driven it.
Somebody moved from one vehicle to another and no matter who it was or what car, the crossing of paths is evident somewhere. There was a transfer/transport at some point in the chronology of things that staying out of Heather's car wouldn't resolve.
I doubt that what happened to her happened at PTL. Unless LE found evidence there they're not talking about, and that's possible, PTL ultimately becomes somewhat of a sidebar, and at the most, a point of connection that was needed for another trip.
So if she did drive there or was driven, I can't imagine she was there for long.